Slime production and antibiotic susceptibility in staphylococci isolated from clinical samples

Abstract

Slime production is considered to be a significant virulence factor for some strains of staphylococci (Christensen et al. 1982, Davenport et al. 1986, Kleeman et al. 1993, Ammendolia et al. 1999, Mack et al. 2000. In coagulase-negative staphylococci (CNS), a loosely bound exopolysaccharides layer (slime) has been found in addition to capsule, and it has been associated with sepsis, including intravenous-catheter-related bacteremia and other prosthetic device infections (Ishak et al. 1985, Diaz-Mitoma et al. 1987, Etienne et al. 1988, Rupp & Archer 1994.Similarly, Staphylococcus aureus strains have bacterial capsules, which are closely associated with the bacterial cell wall. These strains may also have an extracapsular and labile extrapolysaccharidic structure (Caputy & Costerton 1982). Formerly slime production of S. aureus has never been considered as a virulence factor. Recently, some investigators reported that slimeproducing S. aureus strains had a higher colonization capacity than its non-slime-producing variants did. Therefore, S. aureus slime may play a role in the establishment of infection (Baselga et al. 1993, Ammendolia et al. 1999.The importance of the role played by slime is further increased by its frequent association to reduced antibiotic susceptibility (Kloos & Bannerman 1994). The difficulty in eradicating a chronic infection associated with slime formation has been reported, and slime-producing bacteria has been shown to resist higher antibiotic concentrations than non-slime-producing bacteria (Gristina et al. 1987). Moreover, detection of resistance to oxacillin in staphylococci is important to guide the therapy and prevent the patient from being unnecessarily treated with vancomycin, which is an antimicrobial agent that presents therapeutic complications, high costs, and may lead to the selection of resistant mutants (Marshall et al. 1999).In this study, we wanted to evaluate the occurrence of slime production among clinical isolates of both CNS and S. aureus by comparing different methods. To assess the relationship between slime and pathogenicity, we investigated the susceptibility to certain antimicrobial agents, particularly oxacillin. MATERIALS AND METHODSBacterial isolates -One hundred eighty seven staphylococcal isolates, provided by hospital laboratory, were obtained from culture of several specimens; 117 isolated from throat and nasal swabs, 32 from wounds, 21 from urine, 9 from blood, and 8 from catheters. Table I shows distribution of species and clinical samples in the 187 staphylococcal strains. These staphylococcal strains, specifically 115 S. aureus strains, 34 S. epidermidis strains, eight S. chromogenes strains, eight S. hominis strains, three S. saprophyticus strains, one S. lugdunensis strain, one S. capitis strain, one S. haemolyticus strain, one S. warneri strain, one S. cohnii subsp. cohnii strain, isolated from diverse clinical sources were studied. Isolates were characterized at the species level by the API Staph system (Biomerieux, France) according to the instruc...

Analysis of S. Epidermidis icaA and icaD genes by polymerase chain reaction and slime production: a case control study

“…The results of our study are similar to previous literature, in which the percentage of slime-producing strains of S. epidermidis ranged from 31% to 89% [20,21]. In addition, we found a statistical difference with regards to slime production between the clinical isolates from the patient catheter blood specimens and isolates from the nasal vestibules of three groups (p<0.05) (Table 2).…”

Detection of methicillin resistant and slime factor production of coagulase negative Staphylococcus spp. in bovine clinical mastitis by using PCR

“…The data reported here indicate an important role of slime production as a virulence marker for S. epidermidis, where 83.3% of the isolated S. epidermidis were slime producer. These results similar to those reported by [37] who found that clinical CoNS isolates had a high frequency of slime production and drug resistance, particularly S. epidermidis strains.…”

Impact of empiric antibiotic regimen on bowel colonization in neonates with suspected early onset sepsis

“…The different colonization pattern may still have clinical relevance as mucosal colonisation is a potential source of CoNS in invasive infections [14]. Differences in the pathogenicity of CoNS species have been demonstrated with 71% of S. epidermidis but only 35% of S. haemolyticus and 26% of S. hominis strains being capable of slime production, the latter being associated with invasive disease [39][40][41]. The relevance of differences in gut colonization observed in this study is further supported by the clinical findings showing a trend towards greater prevalence of LOS caused by S. epidermidis in the penicillin compared with the ampicillin arm (7.6 vs 2.7 per 100 patient days, respectively).…”